The present invention relates to a method for manufacturing a steering wheel rim for an automobile by using a liquid pressure transfer printing method and an apparatus for cutting a masking tape used therefor, and more particularly, to a method for manufacturing a steering wheel rim for an automobile by using a liquid pressure transfer printing method, in which a masking tape is used in a matching process of a combination portion by a polyvinyl alcohol (PVA) solution when separate transfer printing is formed due to a limit in shape of an object subject to transfer printing so that environmental pollution is minimized due to reduction in the amount of waste water and productivity and reliability of products are improved, and an apparatus for cutting a masking tape used therefor.
Techniques of printing various patterns on a surface of a steering wheel rim for an automobile by using a liquid pressure transfer printing method have been suggested in Korean Patent Application Nos. 17425, 36990 and 36991 filed by the present applicant in 1998.
Also, to improve and automate the above suggested techniques, the present applicant filed Korean Patent Application No. 3368 in 1999 and Korean Patent Application No. 11606 in 1999 as a technique for matching combination of patterns.
In Korean Patent Application Nos. 36990 and 36991 filed in 1998, as shown in FIG. 1, since a first mask member 8 and a conjunction line 8a in the middle must be accurately matched, and after a first transfer printing is performed on a surface a that is a portion which is not masked, a second masking must be accurately performed with an interval of about 0.1 mm from the conjunction line in the middle, an accurate transfer printing work at a boundary surface is very difficult and manufacturing productivity is deteriorated due to a slow work speed. Furthermore, such difficulties have been a factor in the increase of the cost.
Also, since the entire surface subject to transfer printing is masked in the first and second steps, the masking tape is wasted. Further, according to a degree of skill of a worker, the conjunction line 8a in the middle is not matched so that defective products are often generated.
Also, the technique disclosed in Korean Patent Application No. 17425 filed by the present applicant in 1998 is a method in which masking tape and PVA solution are used. In FIG. 1, when the first mask member 8 is attached, tiny pores are generated in a transfer film at a combination portion, forming a non transfer-printing strip due to the thickness of the masking tape during the second transfer printing step. To overcome the above problem, an edge portion located at the conjunction line 8a in the middle of the masking tape 18, that is, the edge of the first mask member 8, is needed to be cut at an inclination angle of about 60xc2x0. However, such cutting is difficult. Also, when the first mask member 8 is removed after PVA coating and drying, after transfer printing is performed on the surface a and the surface is cleaned and dried, the PVA film is not uniformly removed and is unevenly lifted from the boundary surface so that defects, such as mismatch or overlap of transfer printing, are generated.
Also, in Korean Patent Application No. 3368 filed by the present applicant in 1999, the masking tape and PVA solution are used together and a conjunction line in the middle of the masking tape is semiautomatically and uniformly processed by using a predetermined jig.
In the case of mass production by using the above method, a considerable time is needed for drying due to use of a large amount of PVA solution. Accordingly, drying equipment is additionally needed and s-space for drying is needed. Also, cleaning equipment for cleaning the PVA solution is additionally needed. Further, waste water purification equipment is needed due to an increase in the amount of cleaning. When conditions for drying are not proper after the PVA solution coating, the conjunction line is incorrect and thus products may be defective. As a result, due to the above restrictions and problems, the costs of products increase.
To solve the above problems, it is an objective of the present invention to provide a method for manufacturing a steering wheel rim for an automobile by using a liquid pressure transfer printing method; by which mass production is possible, by remarkably improving productivity, the cost for manufacturing a product is considerably reduced by adding minimum equipment so that the existing equipment is effectively used in a limited space, the amount of waste water is sharply reduced so that environmental pollution is reduced, and an unskilled worker can perform an accurate pattern match on the boundary surface during separate transfer printing regardless of conditions for drying.
To accomplish the above object of the present invention, there is provided a method for manufacturing a steering wheel rim for an automobile by using a liquid pressure transfer printing method, which comprises attaching a first masking tape having a predetermined width to a boundary portion of the steering wheel rim to be separately transfer-printed, marking a conjunction line using a blade in a middle portion of the first masking tape attached to the steering wheel rim, with the steering wheel rim placed on a horizontal rotary pedestal, and detaching a lower half portion of the first masking tape, covering an upper portion of the first masking tape which is not detached with a first protective masking tape, performing transfer printing on a surface of the steering wheel rim lower than the conjunction line and cleaning and drying the transfer-printed surface, and removing the first masking tape which has not been detached and the first protective masking tape covering the upper portion of the first masking tape, attaching a second masking tape having a predetermined width to a first transfer printing boundary portion of the steering wheel rim to which transfer printing has been performed, marking a separation line using a blade at a position about 0.05-0.2 mm lower than the conjunction line of the second masking tape attached to the steering wheel rim which is placed on the horizontal rotary pedestal, and removing an upper half of the second masking tape, covering a lower portion of the second masking tape which has not been removed with a second protective masking tape, and transfer printing on an upper surface of the steering wheel rim above the conjunction line and cleaning and drying the transfer-printed surface, removing the second masking tape and the second protective masking tape.
Also, to accomplish the above object of the present invention, there is provided an apparatus for cutting a masking tape used for manufacturing a steering wheel rim for an automobile by using a liquid pressure transfer printing method, which comprises a horizontal rotary pedestal which is rotatable and has a horizontally flat surface on which the steering wheel rim is closely placed, and a clamp provided at the side portion of the horizontal rotary pedestal to fix the steering wheel rim.
It is preferred in the present invention that a plurality of blade holders are formed on the horizontal rotary pedestal, each having a blade moving along the surface of the horizontal rotary pedestal so that a cut line is marked at a predetermined height from the surface of the horizontal rotary pedestal.